Sorbent materials having high surface areas and which have been chemically modified to have catalytic properties are well known for their oxidative and decomposition properties. These properties find use in a variety of fields, in particular the removal and destruction of chlorine, chloramine, trihalomethanes, haloacetic acids, and hydrogen peroxides which are formed when water is disinfected. The sorbent materials are typically formed from various activated carbons and carbonaceous chars which are thermally treated with a nitrogen containing precursor followed by activation to produce the catalytic activated carbon. Alternately, a nitrogen containing precursor can be charred and activated. Activation is normally carried out at high temperature with an activating gas such as steam (water), carbon dioxide, or oxygen. These methods are described in several U.S. patents, including U.S. Pat. Nos. 6,342,129, 6,706,194, 5,356,849, 5,338,458, and 9,174,205, all of which are incorporated by reference in their entirety.
There are disadvantages to the prior art nitrogen pretreatment and activation techniques. The activation process gasifies the surface portion of the carbonaceous char or other sorbent material, which results in small pores being formed as the carbon or other material on the surface of the sorbent particles vaporizes. These pores are responsible for the high total surface area of the sorbent material, and therefore its high performance. However, this gasification during the activation process is not selective to the materials being removed from the surface through vaporization. As a result, much of the incorporated nitrogen which is responsible for the catalytic activity and which is part of the surface skeleton of the sorbent material is removed during the activation process. This is counterproductive and reduces the catalytic properties of the sorbent materials, and therefore its performance in the removal and destruction of deleterious compounds from water.
There is a need for a process which permits the sorbent materials to not only be formed having high surface area that provides for the sorbent properties, but also for the sorbent materials to have increased catalytic functionality. The present invention solves the above and other problems with a novel process that permits sorbents to be formed having both high surface area and excellent catalytic activity.